The protein expression and purification core will provide purified recombinant serpins and other needed proteins from both bacterial and mammalian cell sources to all four research projects. Using bacterial expression plasmids or stably-transfected BHK cell lines, both constructed by the Molecular Biology and Cell Culture core or already available in the laboratories of the investigators, the core will express the required protein by growth of the appropriate cell type, harvest either bacteria or BHK cell growth medium, and isolate the recombinant protein to the high degree of purity required by each project. The core will use established purification methods developed by the investigators for proteins already expressed, but will further optimize protocols to maximize yield and streamline purification. Development for protocols for isolation of new proteins will be the responsibility of the technical director of the core in consultation with the appropriate P.I. The core will provide quality control of the purified protein, by electrophoretic means, functional assay, and where appropriate protein sequencing. The Administrative Director will schedule protein purifications to meet the priorities of the investigators, but with the aim of providing equitable service to all projects. The core may expand beyond the present personnel to meet additional protein needs of the four investigators for other funded projects. However, such additional services will be charged to the other grants.